Glass Castles: The Mystery of Scotland's Vitrified Forts

Glass Castles: The Mystery of Scotland's Vitrified Forts - were these accidental side effects or destruction of these Pictish hill forts or were they intended as a form of architecture?
I explore a number of Scottish Vitrified forts to find out
and concluded at the best example in Aberdeenshire of Tap O Noth
Arthur C Clark's Mysterious World back in 1980 look at the issue and I revisit that tv show

#taponoth

[julesdingle]

AMAZING COMMENTS thank you- [and yeah probably dragons ]
As with many film projects by the time they are finished I have developed my ideas more fully- I'm not sure if its clear in the video but I conclude that whilst discovery of vitrification might have been accidental the architectural skills were developed to make a rubble wall more pleasing and durable.
Modern science has failed to reproduce the results - but given a big enough budget I would suggest that a timber framing filled with rubble could be fused with charcoal being introduced in quantity with the rubble infill and the wall insulated in turf.
what do think? And if you have had experience with dry stone walling how would you recreate these glass walls?

[dmcclure-kysc]

For the IRON AGE to take place, the technology of creating large quantities of charcoal from mounds of oak logs covered in turf with a weeks-long controlled had to be developed.

A similar technique was then developed for smelting iron ore by placing the charcoal and crushed ore inside an earthen kiln, and creating a very hot fire with a forced air draft.

From the melted contents of the kiln, the lower melting silicate minerals would first be drawn out in a crude glassy slag, and then the remaining iron bits would congeal into a so called "bloom" which was then further worked into a solid mass of iron.

Thus the techniques of the earthen kiln and controlled fire had already been developed.

Now, glassy slag and more charcoal were readily available materials to the builders.

One might imaging that after observing molten slag glass drained from a smelter fusing together rubble around the base of the smelter, the thought arose that this same slag material might be re-melted to intentionally fuse a mass of masonry pieces together, with a lot of very careful planning.

Therefore, an empirically developed mixture of crushed previously melted slag and charcoal fuel could have been placed ( as a dry mortar-like infill) between the dry laid stones of the fort wall during its initial construction.

Then similar to the charcoal kiln, a turf covering could allow controlled airflow to later fire the core of the wall. A firing to briefly re-melt the crushed slag, allowing a thin layer of melt to bonds adjacent wall stones would be sufficient; thus forming an intermittent glass "mortar" connecting the stones into an immovable mass.

Drainage saps in the mass left by burnt charcoal might have reduced the chances of frost later cracking the wall apart.

Quite likely, the exterior turf cladding would simply have been left in place in the finished product, as they were in so many other dry stone wall constructions.

Sections of un-fired wall constructed as above still serve their immediate defensive function, which would allow the carefully controlled firing process to take place at a later date as the availability of time and skilled individuals allowed.

While this comment is submitted as informed speculation only, the various components are well established historically, and the leap of using the waste slag for a such higher purpose is exactly the kind of idea that might present itself to someone who had already mastered the task of extracting and using the iron portion of the smelter contents.

[lorenstribling]

The ancient castles are fascinating but the real beauty here is Scotland itself.

[TheMadmacs]

i suspect they surrounded the walls with greggs sausage rolls, which contain more heat for longer than fuel rods at a power station.

[margomoore]

In childhood, I recall reading a tale of a young hero attempting to climb a glass tower riding his horse. It seemed impossible. But a fort with vitrified walls—maybe. I figured sooner or later some remnants of a glass tower would show up. Glad they have!

[elultimopujilense]

Those views of Scotland are just majestic! What a beautiful country!

[caoimhekeohane]

Brillliant to see a deep dive into vitrification! I live near Inverness so this was great to watch. Many thanks!

[Peter-MH]

Very interesting! It seems things during the Iron Age, and even earlier, were much more sophisticated and organised than generally thought.

[circumnavigator]

We do not give ancient peoples nearly enough credit. Wish I could have seen some of these while I was over there. Great work. Awesome that you've been able to document so many sites

[kennyhagan]

I saw that show! I was just starting my junior year in high school and I was fascinated by the fact that the stones were fused by heat. I even went to the trouble of asking both my history and chemistry teachers how they thought it might have been accomplished.
Thanks for bringing back some interesting memories.

[lee.mclaughlin]

Thank you for talking about this topic I have been deeply fascinated with this subject for a while now and thought it was mad how little people know about this, I am from Scotland and almost no one knows about this.

[AlannahRyane]

I love this so much! My lens is into the royal family moving to Ireland and Scotland after the fall of Armana. The Milesian descendants, round towers etc... Great job.... 🙂

[jimjolly]

I visited the vitrified fort of Dun Skeig. Given its location, the extra effort in bringing the wood required to burn it after capture would seem unnecessary, whereas vitrification as a means of binding small stones and strengthening an otherwise unstable structure makes a lot of sense. Fascinating video, thanks!

[addersbowman]

As a glass maker who melts sand into glass every day, i can say that you would need to achieve temperatures of over 1800C to vitrifie rock. This is simply not possible by around 1000C using the techniques suggested here.

[CSGraves]

Fascinating process.... the use of James Horner's Krull score is icing on the cake for me 😄

[PhatChic]

another fascinating insight into a subject matter that was alien to me. you really would have been the coolest teacher in school

[davidnorwich]

Wow the mysteries of Scotland! Glass walls. Who would have though that someone in the distant past would come up with that idea? I loved this video and also the comments.

[pks]

Your sentences regarding Clarke in the 80s were exactly mine back then too. I bet we watched the original same airing. I was scrolling through YT and saw vitrified forte and had to watch. Superbly interesting, thanks.

[johnakyle]

I'm near Dun Deardail Fort in Glen Nevis and always have found it worth a visit, such a great setting, commanding views down the Glen .I was unaware there were so many of these forts in Scotland.

[geolyn]

This was new to me. How fascinating! Your photography is gorgeous too.